| 摘要 |
PURPOSE: To enhance resistance to fatigue failure by defining at least a part of a frame member by a single guide strip forming two guide channels and making the guide channels facing inward apart by a strip material defining a channel facing outward. CONSTITUTION: The guide strip 60 is formed to substantially W-shape in cross- section by deforming a cold rolled steel sheet. The W-shaped cross-section forms a pair of guide channels 61, 62 facing inward and receives a frame part of a metallic net 18. The two channels are made apart by an intermediate channel 63 facing outward and side parts 64 thereof are parallel to each other. Thereby two V-shaped profiles 65 are apart from each other. An external profile having smooth projected surface is formed between the profile 65 and a frame part of the strip 66 to support a filter element 11. The strip material is folded by being bent inward to be the frame part so that a free frame part 66 reinforces the frame part without injuring a filter element 11. Thereby resistance to fatigue failure is enhanced.
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